Mechanisms for reproducing (playing back) information are in the focus of many technical areas. Usually, the information which is intended for reproduction is contained on a physical medium, which is read out using suitable devices. The read-out information is then reproduced optically, acoustically, optically and acoustically combined, or in another perceivable way.
Various circumstances in connection with the handling of the medium make identifying it (or copies obtained therefrom) seem desirable. Thus in the production of media, there is often the requirement to provide the media with an individualizing identification such as a running serial number or batch designation. Such identification makes it easier subsequently to determine production sites, production parameters, sales routes, media copies (and/or the corresponding master media), etc.
In general, the medium is identified by, for instance, a serial number being applied to a surface of the medium using suitable printing or engraving techniques. To avoid affecting the reproduction of the information, care is taken that the identification is applied separately from those areas of the medium which contain information which is intended for reproduction.
In practice, it has been found that traditional identifications are frequently manipulated, intentionally and unintentionally.
The invention is based on the object of giving an improved approach to the identification of a machine-readable medium which contains information intended for reproduction.